Secondary footprint assignment

It is sometimes useful to have a secondary/alternate footprint to assign to a part, and that can be selected for use in pcbnew. One example use case is when placing 0402 components under BGA parts, as the pads of the 0402 part need to be hexagonal in shape to fit. It would be a great feature to be able to assign secondary footprints in eeschema and be able to quick toggle the footprint association in pcbnew.